Preheat the oven to 350 F. In a medium bowl, whisk together flour, salt, baking soda, and cream of tartar. In a large bowl, combine butter and sugar until fluffy.
Add in egg and vanilla extract, and mix until smooth. Add in the flour mixture, and mix until it is fully combined. Roll the cookie dough into balls, and place them onto a large ungreased baking sheet.
Bake for 10-12 minutes. Remove from the oven and top each cookie with one chocolate kiss.